1. Field of Invention
This invention relates to fluidic angular rate sensors, more particularly to apparatus for compensating dynamic null offsets.
2. Description of the Prior Art
Of the fluidic angular rate sensors known in the art, perhaps the most widely used is the type illustrated in Schuemann U.S. Pat. No. 3,587,328, which comprises a self-contained unit including a piezoelectric diaphragm pump, and a fluid jet (or nozzle) through which a suitable fluid, such as an inert gas, is forced by the pump, thereby providing a charge or stream of gas directed toward a pair of temperature sensitive resistive elements which are differentially cooled by the jet whenever the jet is moved (such as in angular rotation) in a plane of sensitivity. The sensing elements are typically fine tungsten wires disposed on opposite sides of the center line of the nozzle boresight and perpendicular to the plane of sensitivity of the device. This device has found favor in many applications since it has no rotating parts, and substantially no moving parts (none except the vibrating diaphragm of the fluid pump).
One utilization of fluidic angular rate sensors (due to the lack of rotating parts) is in long storage life applications. In such cases, despite the care taken during manufacture and initial calibration, aging of the components and of the casing and other mechanical parts can easily cause changes in operating parameters which were initially adjusted for very accurate operation. The errors introduced in the rate sensor through aging can in turn create errors of a mission-failing magnitude in an overall system in which it is used.